Abstract—Study of biodelignification of rice straw was investigated by using a fungus isolated from indigenous the straw. Identification of the fungus was characterized by 18s rRNA sequencing and included in the new species of Penicillium sp. strain apw-tt2. Ligninase production and cell growth was observed in incubation condition of Submerged Fermentation (SmF). Optimizations of the enzyme production condition were carried out by altering pH and temperature of the incubation medium. The results showed that the optimum conditions for biopulping are at 40˚C and pH 5. High ligninase production was observed at Day 4 with activity 571 U/ml with degraded lignin 66.3%. The quality of pulp showed that the new species is very effective in delignifying rice straw for pulping. Index Terms—Penicillium sp., delignification, 18s rRNA, ligninase, biopulping I. INTRODUCTION Indonesia as an agricultural country producing rice straw with a very large amount, however the straw is still regarded as a waste which will ultimately be burned without further utilized. Delignification is a process separation of lignin from cellulose. Removing lignin by chemical method still widely used mainly as a method of pulping industry and this process is very important in the industry of pulp and paper. Biopulping needed in the industry since delignification process can be environmentally friendly and reduce the cost of production. Process of making pulp (cellulose fiber) are biologically using ligninolytic microorganism. The most efficient fungi for lignin degradation are included as white rot-fungi which produce ligninase that capable to modify lignin from organic material such as wood, bamboo, or straw. The enzymatic system of ligninase comprising of laccase and peroksidase which has been consider as a useful enzymes for the improvement of biotecnology process for biopulping and biobleaching. Most researches showed that white-rot fungi as effective lignin decomposer such as Phanerochaeta chrysosporium[1], Agaricus bisporus [2], Pleurotus ostreatus [3], Bjerkandera adusta [4], Curvularia lanata [5], Pleurotus sajor-caju [6],[7]. The soft rot fungi (Ascomycetes) capable to decompose lignin as well. Aspergillus fumigatus, A. Manuscript received October 15, 2012; revised November 20, 2012. This work was supported in part by The Ministry of Education National, Indonesia. Asri Peni Wulandari is with the Universitas Padjadjaran, Indonesia (e-mail: [email protected]). Tika Triyana and Poniah Andayaningsih are with the Department of Biology, Universitas Padjadjaran. japonicas, A. niger, A. terreus [8], Penicillium sp. [9] and P. chrysosporium [10] have the ability to degrade aromatic compounds such as lignin. Quality of pulp can be seen from the ratio of lignin and cellulose. Pulping process produces pulp of good quality when producing low levels of degradation of cellulose in the presence of high level lignin dissolution. Comparison between biopulping and chemical pulping processes based on the percentage of reduction in lignin content shows the results of each are 44.05% and 56.41%. Several studies have shown that biodegradation of lignin by fungi ligninolytic reduced lignin content by 20 - 30% within 60 days, when delignification performed on sawdust reduced the lignin 19% while the cellulose by 6% for 60 days [11]. For the purpose of producing ligninase, ligninolytic fungi will have a higher activity when incubation condition using submerged fermentation technique or Submerged fermentation (SMF) compared to solid fermentation or Solid State Fermentation (SSF) [12]. The aim of the study was to investigated the potency of straw-indigenous Penicillium sp. strain apw-tt2 capable of producing ligninase for biopulping process. II. MATERIAL AND METHODS A. Rice Straw Rice straw used in this study were collected from Arboretum, Universitas Padjadjaran, West Java, Indonesia. Isolate Penicillium sp. strain apw-tt2 is a collection of Laboratory of Microbiology, Department of Biology, Padjadjaran University, Indonesia. B. Enzyme Preparation and Assay Enzyme Commercially available Kraft lignin (Sigma) was used throughout this study. Modification of enzyme preparation and assay enzyme were carried out according to assay ligninase [2], [7]. Crude enzyme extract ligninase was taken (1 ml), centrifuged for 20 minutes at 2000 rpm. The supernatant was taken 0.4 mL then mixed with 0.5 mL of 100 mM acetate buffer pH 5 and 0.1 mL of lignin [2]. This mixture was fed into the cuvette and incubated for 10 min at 30˚C. The absorbance of the sample was measured at a wavelength of 383 nm. Observations were made every 24 hours for 10 days. Each sample was tested twice (duplicate). One unit of activity was defined as the ligninase which released for 1 μmol product per min or increase in absorbance at 383 nm per min per ml assay mixture at pH 5. Delignification of Rice Straw with Ligninase from Novel Penicillium sp. strain apw-tt2 for Biopulping Asri Peni Wulandari, Tika Triyana, and Poniah Andayaningsih International Journal of Bioscience, Biochemistry and Bioinformatics, Vol. 3, No. 1, January 2013 43 DOI: 10.7763/IJBBB.2013.V3.160
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Abstract—Study of biodelignification of rice straw was
investigated by using a fungus isolated from indigenous the
straw. Identification of the fungus was characterized by 18s
rRNA sequencing and included in the new species of
Penicillium sp. strain apw-tt2. Ligninase production and cell
growth was observed in incubation condition of Submerged
Fermentation (SmF). Optimizations of the enzyme production
condition were carried out by altering pH and temperature of
the incubation medium. The results showed that the optimum
conditions for biopulping are at 40˚C and pH 5. High ligninase
production was observed at Day 4 with activity 571 U/ml with
degraded lignin 66.3%. The quality of pulp showed that the new
species is very effective in delignifying rice straw for pulping.
Index Terms—Penicillium sp., delignification, 18s rRNA,
ligninase, biopulping
I. INTRODUCTION
Indonesia as an agricultural country producing rice straw
with a very large amount, however the straw is still regarded
as a waste which will ultimately be burned without further
utilized.
Delignification is a process separation of lignin from
cellulose. Removing lignin by chemical method still widely
used mainly as a method of pulping industry and this process
is very important in the industry of pulp and paper.
Biopulping needed in the industry since delignification
process can be environmentally friendly and reduce the cost
of production.
Process of making pulp (cellulose fiber) are biologically
using ligninolytic microorganism. The most efficient fungi for
lignin degradation are included as white rot-fungi which
produce ligninase that capable to modify lignin from organic
material such as wood, bamboo, or straw. The enzymatic
system of ligninase comprising of laccase and peroksidase
which has been consider as a useful enzymes for the
improvement of biotecnology process for biopulping and
biobleaching.
Most researches showed that white-rot fungi as effective
lignin decomposer such as Phanerochaeta chrysosporium[1],